The present disclosure relates generally to the field of data storage, and more particularly to data recovery and preventing data storage loss.
HyperSwap (e.g., logical device swapping) is a function provided by IBM's z/OS operating system. An event which causes a logical device swap to be initiated is called a swap trigger. Logical device swapping provides continuous availability of data when disk failures occur by maintaining synchronous copies of all primary volumes on one or more secondary volumes. When a disk failure is detected, code in the operating system identifies volumes managed with logical device swapping and instead of failing the I/O request, the system switches (e.g., or swaps) information in internal control blocks so that the I/O request is driven against the secondary volume of the synchronous copy. Since the secondary volume is an identical copy of the primary volume prior to the failure, the I/O request will succeed with no impact on the issuing program. The disk failure is therefore masked from the program and avoids application and system outages.